Stereoscopic images have utility in a number of fields where accurate perception of the spatial relationship of various parts of the subject is important. Examples include interpretation of aerial photographs, visulaization of anatomical features in tomographic images, and operation of remote manipulators in hazardous areas or in outer space. Historically entertainment has also been an area of interest because of the increased visual impact three-dimensional images have compared to two-dimensional images.
Conventional stereoscopic systems require either that the observer peer into a set of eyepieces which present each eye with the appropriate member of a stereo pair, or that he wear a pair of spectacles or goggles which filter a double image on a screen so that each eye receives only one of the images. The inconvenience of these requirements has resulted in a number of attempts to present directly viewable three-dimensional images which can be observed with the same freedom as two-dimensional images. Development of such autostereoscopic systems has proven to be a difficult technical task. Holograms and lenticular screen hard copy approaches have had some success, but film projection and television approaches have not gotten much beyond the laboratory stage. In particular, most technically feasible prior art approaches have limitations such as double image zones, pseudoscopic image zones, very limited areas in which proper viewing is possible, and dark lines in the image field. Further, several systems intended to present autostereoscopic images have been proposed and patented which contain conceptual flaws which make them incapable of presenting a three-dimensional image.
The prior art concentrates on film based autostereoscopic displays, and provides little guidance on means of achieving this result using television. In particular, the scanning nature of television image formation, which is quite different from film image formation and presents a unique set of problems and opportunities, is not addressed.
The central features of this invention are improvements which eliminate the image flaws found in many of the prior art systems, a novel way of taking advantage of the scanning nature of television which results in a uniquely efficient and simple autostereoscopic display and a major improvement in individual viewing devices for large screen presentations.